The long-term goal of this study is to develop knowledge of the relationship of prostatic hyperplasia (BPH) and prostatic cancer. The principal specific aims are evaluation of the prostatic cancer mortality rate subsequent to surgically-confirmed BPH and comparison of prostatic cancer incidence and death rates according to histologic features of BPH. A retrospective follow-up study is proposed. A population-based group of 6,000 men with surgically-confirmed BPH will be identified by use of pathology records in Rhode Island hospitals state-wide. Subjects will have had their index admission in the period 1959-70, and will have been less than 75 years old at that time. The cohort will be followed up by use of medical records, death certificates, city directories, and other existing resources. Slides of the benign tissue will be retrieved for all the cases of prostatic cancer that are identified, and for a sample of 3 times that number of non-cases. The slides will be reviewed according to a standard protocol in order to assess the features of the hyperplastic tissue, especially the epithelial component, and other benign changes. The death rate from prostatic cancer in the cohort will be compared to the rate experienced by Rhode Island men of similar ages. By use of the case-control within a cohort approach, the incidence and mortality rates from prostatic cancer will be correlated with histologic features of the benign tissue removed. Death rates from other causes also will be evaluated. The findings will bear on the natural history of prostatic hyperplasia, and on the clinical prognosis of men with this condition.